main vent open pipes

Unknown

I would assume that I would want my main vents to wind up with the same cfm's. But if this where a one-pipe steam with only one main vent, what variables would make me chooses between a 1/2", 3/4", or 1" tapping ?

JK_3

open steam main vents

Per the "Balancing Steam Systems Using a Vent Capasity Chart," how does anyone know either to use a 1/2",3/4",or 1" tapping for their main vents.
I'm using this to balance a one-pipe steam system.Off the header it goes off in two directions to two main vent locations. How do I know what size tapping to put in ? The lengths of the steam mains are different. Both are 2" pipe. One is about 15' to the main vent location off the header, and the other is 25' to the main vent off the header. I want them to vent at equal times for even heat in the whole building. This is a four-story brown stone building. Thank you.

Patrick Linhardt, \"Linhardt's Field Guide to Ste

vent question or . AIR OUT

> I would assume that I would want my main vents to

> wind up with the same cfm's. But if this where a

> one-pipe steam with only one main vent, what

> variables would make me chooses between a 1/2",

> 3/4", or 1" tapping ?



Hi KC,

You are on the right track, balancing the venting of the steam mains to achieve even heating on a one pipe system.
Use a 3/4" tap to give some flexability on vent selection.
Don't assume the same vent rate in cfm for any main. The determining factor is the size of the pipe and the length of the pipe. Taken together, they can predict how much air in cubic feet there is in the main at start-up. That is what we want to get rid of at the smae time, both mains to be able to release the air in about 2 to 5 minutes, generally the faster the better (mo venting - mo better).

So calculate the amount of air in the main, 2" pipe contains about .023 cubic feet per foot. Multiply that times the length, then divide by the rates of potential vents. Find some combination that balances out the removal of air from the mains.

Good luck

Patrick Linhardt, \"Linhardt's Field Guide to Ste

vent question or AIR OUT

Hi KC,

You are on the right track, balancing the venting of the steam mains to achieve even heating on a one pipe system.
Use a 3/4" tap to give some flexability on vent selection.
Don't assume the same vent rate in cfm for any main. The determining factor is the size of the pipe and the length of the pipe. Taken together, they can predict how much air in cubic feet there is in the main at start-up. That is what we want to get rid of at the same time, both mains to be able to release the air in about 2 to 4 minutes, generally the faster the better (mo venting - mo better).

So calculate the amount of air in the main, 2" pipe contains about .023 cubic feet per foot. Multiply that times the length, then divide by the rates of potential vents. Find some combination that balances out the removal of air from the mains.

Good luck.

Best regards, Pat

Unknown

This first Time I tried this,I removed the 3/4" tapping and timed how long it took for the air to get out. That # was 4 min. I installed 4 gorton # 2's and 1 Gorton # 1 to match 9.5 cfm's of the open pipe. Testing it, it took 7 min. to get the air out. If I added the cfm's of the main to the cfm's of the open vent I would have gotten a different #. That would've meant more vents, but alot closer to my 4 min.
Now when sizing my Rad vents with the two mains, I time how long it takes for the air to get out and that my # for my rad vents. So if one main takes 2 min., I use #2 to divide my Rad cfms. If the other side is 4 min. than, so on... Thank you very much !!

Unknown

to conclude this, would this be correct ?

Unknown

on a different question;
Normally the main vent goes after all the supply tees 15" before it drops down. If at the end of the main you have 3 tees taking up that space, would it be a big deal to tap the main vent between 2 of them. This main is short and only has 4 take-offs. So the main vent would have 2 tees on each side of it.

For the two take-offs that would be after the main vent, one goes to a radiator on the frist floor directly above, and the other is a riser that goes up 4 stories.